investigators also want to question tamerlan tsarnaev's wife. the couple initially met at a nightclub. she later converted to islam, dropped out of college and had a child with him. her attorney has said that she had no suspicions that her husband might be plotting an attack. hundreds of people stood in silence at copley square at 2:50 p.m. one week after the bombings. president obama marked the moment of silence from the white house. the u.s. senate held a similar tribute on capitol hill. >>> it is still unclear what impact the boston bombings will have on the immigration debate in congress but the topic of national security is clearly playing a more rom neprominent n the discussion. things got tense on capitol hill yesterday when senator chuck schumer sparred with republican senator chuck grassley about the future of the legislation. take a look. >> a few ways to improve the bill, offer an amendment when we start mark-up in may and let's vote on it. i say that particularly to those who are pointing to what happened, the terrible tragedy in bos